Radial form ultra-high frequency tube



Oct. 13, 1942.. c v, LITTON 2,298,949

RA DIAL FORM ULTRA-HIGH FREQUENCY TUBE Filed April 20, 1940 2 Sheets-Sheet 2 INVEN TOR.

CHARLES V. L/TTON ATTORNEY.

Patented Oct. 13, 1942 UNITED sT T nanmr. romvrun'rm-mdnranounncr Charles V. Litton, Redwood City, assignor to International Standard Electric Corpora- I tion, New York, N. Y; acorporation oi' nela- -ware Application April 20, 1940, Serial No. 330,662

9Claims. (Cl. 250-215) This invention relates to ultra-high frequency velocity modulated tubes, and more particularly to velocity modulateditubes wherein'the' emitted electrons are radiallyisiipplied to annular resonant cavities.

Tubes are known in. which electrons emitted from a cathode are accelerated-in a given direction and caused to pass by control electrodes, the control electrodes being associated with a resonant circuit so that electrons are alternately accelerated and decelerated while passing the;

control electrodes. After passing the electrodes the electronstreamis caused to traverse a given I distance so that the electrons become grouped, due to their difference in velocity, the grouping following a particular wave formation. A 'second resonant circuit is then provided and electrode arrangements in this second circuit are energized in such phase as to absorb the energy from the grouped electron waves.

This known type of tube has been constructed so that the electrons are emitted in a single concentrated beam, and the resonant circuits and control electrodes are provided in tandem along this beam. This type of arrangement limits the power that can'be obtained since the limited area permits the building up of a space charge which limits the space current practically useable.- v Q I Acording to my'invention, I provide a velocity modulated tube of the above type which permits the handling or generation of greater powerthan the previously known systems.

This is accomplished according to one feature of my invention by providing a cathode from which electrons are emittedradially, and accelerated to produce a substantially continuous radial sheet or disc-like beam, and providing control and absorption electrodes of annular form for modifying the electron velocity. The resonant circuits are also made in the form of annular chambers. It is apparent thatthe outer resonant chambers are larger in dimensions, re-' ducing the space charge, effects even with large space currents by reason of the increased effective area.

According to a further-feature of my invention I provide, convenient means for adjusting the spacing of said annular electrode systems to adjust the tuning of the system. 7 A still-further feature of my invention comprises a magnetic ,pontrol arrangement for preventing the electron sheet from spreading laterally.

A better; understanding of my invention as which i v Fig. 1 shows a simple form of a tube in accordance with my invention,

Fig. 2 shows a further preferred structural arrangement of a tube in accordance with my invention together with tuning means therefor;and-

Fig. 3 illustrates a form of magnetic control arrangement and tube structure: in accordance with myinvention. In Fig. 1 is'illustrated in a form of tube'in accordance with my invention which serves to illustrate the principles thereof. The tube generally designated at In comprises an electron emissive cathode I l supplied by suitable heating means. Around cathode II is provided an annularochamber l2 and centrally disposed in the walls of chamber [2 are grids l3; l4. Annular chamber [2 is connected by means of a flange passage IS with a further annular resonant chamber 22. The annular chamtional view thereof corresponds substantially to a pair of quarterwave transmission lines connected end to end. Thus the chambers are designed to-resonate at a desired frequency. Electronsemitted from cathode H are accelerated outwardly in a radial direction through grids l3, [-4 by means of a high potential applied to resonant chambers l2 and I3 by any suitable means, not shown.

The spacing of grids I3, H is adjusted so that as'the electrons pass through these grids they are alternately accelerated and retarded. As the electrons leave grid M and pass through the annular chamber i 5 they tend to become grouped because" or. the diiferent relative velocities. Resonant chamber 22 oscillates at the same frequency as chamber 12 but the phase relation of its-oscillations with respect to those of chamber is adjusted so as to tend to slow down the electrons and extract energy the frequency of whichdepends upon the electron grouping from the groups. Thus, grid I6 arranged in resonant chamber 22 serves to slow down the electrons and extract the energy therefrom. The output energy from the tube may be fed over a trans-- mission line illustrated in'section at I! to any cross sectional view' desired output device. If the tube is to serve as an oscillation generator a feedback circuit is provided, as shown at 18 between resonant chambers l2 and 22. The vacuum within the chamber may be maintained by means of-aclosure member l9 and glass seal member 20 which serves also as a seal for the lead-in wires for the cathode I I.

By this annular arrangement an increased area is obtained as the electrons leave the cathode and traverse radially toward the working circuit. This increase in spacing has the advantage that large space currents may be handled within the tube without causing an undue space charge effect.

In Fig. 1 I have shown one particular form of my invention. Fig. 2 illustrates a further preferred embodiment which incorporates further means for adjusting the'spacing between the grids such as l3. Furthermore, in the arrangement of Fig. 2 the resonant chambers are made lower and flatter than shown in Fig. 1 and a separate additional target arrangement is provided so that the electrons leaving the absorption circuit 22 may be further retarded by a different potential applied to an additional collector electrode 30. v

The tube arrangement of Fig. 2 comprises more particularly a cathode ll supported from a glass seal 20. The control grids l3, l4 associated with resonant chamber l2 are adjustable in spacing. This adjustment may be accomplished by mounting grid 13 on segmental plates 3i and providing slots 32 in the inner wall of the resont chamber [2. Inner wall of chamber [2 is preferably made inclined. Mounted within the tube and in contact with the various portions of wall 33 between the separate slots are a plurality of rods 3| mountedon an inturned portion 35 of the tube envelope. Portion 35 is connected by means of a metal bellows with the outer portion of the envelope. Arranged above the metal bellows 36 is provided a cap member 31 fastened at its lower end by a ring 38 provided on the envelope. within the cap member 31 are adjustable screws 39. By adjusting screws 39, member 35 together with rods 34, may be raised or lowered controlling the position ofthe slotted portions of the inner wall of chamber [2- thus moving the grid segments 3| away from or closer to grids It so as to adjust the spacing for tuning purposes. The drift distance between grid H and the grid I6 associated with resonant chamber 22 is controlled by means of an annular passageway [5. Associated with grid IS in chamber 22 is a second grid member Ml so that electrons leaving cathode Il pass first through grids l3, H where they are given modulation in velocity and then after traveling through chamber I5 pass through grids l6 and 40 where their energyis absorbed in the annular resonant chamber 22. From chamber 22 energy may be extracted by means of the coupled transmission line H. After leaving grid 40 the electrons pass outward to the collector electrode 30'. Collector electrode 30 is insulated from the metal envelope portions of the tube by suitable means: such as the glass seal 43, so that electrode 30 may be maintained at a different potential lower than that of the casing. Accordingly, the electrons after passing electrode 40 are deceleratcd further by'target electrode 30. so that upon contacting this electrode they do not release so great an amount of heat. If the tube is to be utilized as an oscilla- Threadily adjustable tion generator, afeedback loop arrangement II is provided between chambers 22 and I2.

By making the resonant chambers relatively low and flat as illustrated in Fig. 2, the power requirements of the tube may be enhanced over the arrangement shown in Fig. 1. Any desired power requirements can be met merely by increasing the diameter of both the toroidal resonant chambers and similarly increasing the dimeter of the cathode. Upon increasing the dimeter of the cathode a ring shape may be given thereto. Thus, the area of the resonant chambers may be radially increased by this increase in diameter so as to care for larger space currents in accordance with the power requirements of the circuit.

In Fig. 3 is illustrated a still further embodiment of my invention. In this arrangement a tube having generally the same type of construction as shown in Pig. 2 is illustrated. In this arrangement, however, the cathode II is made in the form of a ring as described above. Furthermore. the concentration of the electron sheet leaving the cathode II isenhanced by utilizing a magnetic focusing arrangement for preventing the spreading of the field. This magnetic arrangement comprises twq iron shell arrangements 50, 5| made in annular form and provided with coils I2, 63. This magnetic circuit tends to concentrate the electrons emitted from cathode H so as to maintain them in a flat disc-like beam. The magnetic circuit arrangement is arranged similar to two dynamic speaker field coil assemblies properly phased in opposition so that both magnets contribute to the magnetic flux along the electron path. By use of this arrangement at greater concentration of the beam may be achieved and improved operating characteristics may result.

While I have described my invention in connection with a few simple preferred embodiments thereof, it should be distinctly understood that these embodiments constitute merely a preferred form of my invention and not a limitation on the scope thereof. Many other types of tubes may be constructed utilizing the principles of my invention without departing from the spirit thereof. WhatI consider to" be my invention and upon which I desire to obtain protection is embodied in the accompanying claims.

trodes mounted about said cathode in the pathof said electrons, a first resonant circuit coupled to said control electrodes to alter the-velocity of said electrons, an absorption electrode means mounted outside said first resonant chamber in the path of said altered velocity electrons, means for guiding said electrons from said control electrodes to said absorption electrode means, and a second resonant circuit coupled to'said absorption electrode means.

2. A high frequency tube according to claim 1 wherein said first and second resonant circuits comprise annular chambers forming a part of the envelope of said tube.

3. A high frequency tube according to claim 1, further comprising magnetic control means cou ially disposed with respect to said cathode and producing a magnetic field along the path of said electrons between said cathode and said absorption electrode whereby said electrons are her in the form of avhollow annulus mounted about said cathode, control electrodes in the walls of said first chamber in alignment with said cathode for imparting to the electrons emitted a variation in velocity dependent upon the oscillating frequency of said first resonant chamber, a. second resonant chamber in the form 01 a hollow annulus mounted outside said first resonant chamber tuned to said oscillating frequency, an absorption electrode in the wall of said secondresonant chamber in alignment with said control electrodes and said cathode, said absorption electrode being spaced a distance from said control electrodes dependent upon said frequency, and means for confining emitted electrons substantially in a radial path from said control electrodes to said absorption electrode.

5. A high frequency tube according to claim 4, further comprising a collector electrode in annular form mounted outside said second annular chamber in substantial alignment with said absorption electrode, and means supporting said collector electrode in insulated relation with respect to said chambers, whereby a different voltage may be applied thereto.

6. A high frequency tube according to claim 4, wherein the wall of said first chamber adjacent said cathode is provided with slots dividing the electrode support thereof into segments,

further comprising means cooperating with said' slotted wall portions for adjusting the, position of said segmented electrode support, and new external of said tube for controlling said last named means.

'7. An ultra high frequency tube of the velocity modulation type comprising a pair of concentric members of substantially cylindrical form effectively closed at both ends and forming an annular cavity, two velocity modulating electrodes connected respectively to said members near the centers thereof and having openings for the passage of electrons, means for producing a stream of electrons passing successively through said openings in said two electrodes transversely to the longitudinal axis of said members, means for establishing oscillations in said cavity between said pair of members to cause said two electrodes to velocity modulate said stream of electrons, and means for extracting high frequency energy from said velocity modulated stream of electrons after the electrons thereof have become bunched due to said velocity modulation, said means for establishing oscillations comprising a feed-back connection between said extracting means and said concentric members.

8. An ultra high frequency tube according to claim 7 wherein said pair of members of substantially cylindrical form have a length substan- .1, further comprising magnetic control means comprising a pair of generally similar coils CHARLES V. LIT'ION. 

